diff --git a/lib/common_test/doc/Makefile b/lib/common_test/doc/Makefile
index 236b312853af..66722a56f7c5 100644
--- a/lib/common_test/doc/Makefile
+++ b/lib/common_test/doc/Makefile
@@ -26,7 +26,6 @@ include $(ERL_TOP)/make/$(TARGET)/otp.mk
 include ../vsn.mk
 VSN=$(COMMON_TEST_VSN)
 APPLICATION=common_test
-EX_DOC_WARNINGS_AS_ERRORS=false
 
 # ----------------------------------------------------
 # Release Target
diff --git a/lib/common_test/src/ct.erl b/lib/common_test/src/ct.erl
index f35b0c43e20b..31cd89ea56f5 100644
--- a/lib/common_test/src/ct.erl
+++ b/lib/common_test/src/ct.erl
@@ -20,8 +20,6 @@
 
 -module(ct).
 -moduledoc """
-Main user interface for the Common Test framework.
-
 Main user interface for the `Common Test` framework.
 
 This module implements the command-line interface for running tests and basic
@@ -506,7 +504,7 @@ require(Name,Required) ->
 -doc(#{equiv => get_config(Required, undefined, [])}).
 -spec get_config(Required) -> Value
       when Required :: KeyOrName | {KeyOrName, SubKey} | {KeyOrName, SubKey, SubKey},
-           KeyOrName :: atom(),
+           KeyOrName :: key_or_name(),
            SubKey :: atom(),
            Value :: term().
 get_config(Required) ->
@@ -515,7 +513,7 @@ get_config(Required) ->
 -doc(#{equiv => get_config(Required, Default, [])}).
 -spec get_config(Required, Default) -> Value
       when Required :: KeyOrName | {KeyOrName, SubKey} | {KeyOrName, SubKey, SubKey},
-           KeyOrName :: atom(),
+           KeyOrName :: key_or_name(),
            SubKey :: atom(),
            Default :: term(),
            Value :: term().
@@ -574,7 +572,7 @@ See also [`ct:get_config/1`](`get_config/1`),
 """.
 -spec get_config(Required, Default, Opts) -> ValueOrElement
       when Required :: KeyOrName | {KeyOrName, SubKey} | {KeyOrName, SubKey, SubKey},
-           KeyOrName :: atom(),
+           KeyOrName :: key_or_name(),
            SubKey :: atom(),
            Default :: term(),
            Opts :: [Opt],
@@ -597,7 +595,7 @@ aliases.
 -doc(#{since => <<"OTP R14B">>}).
 -spec reload_config(Required) -> ValueOrElement | {error, Reason}
       when Required :: KeyOrName | {KeyOrName, SubKey} | {KeyOrName, SubKey, SubKey},
-           KeyOrName :: atom(),
+           KeyOrName :: key_or_name(),
            SubKey :: atom(),
            ValueOrElement :: term(),
            Reason :: term().
@@ -661,7 +659,7 @@ escape_chars(Format, Args) ->
 	    {error,Reason}
     end.
 
--doc(#{equiv => log(default, ?STD_IMPORTANCE, Format, [], [])}).
+-doc "Equivalent to [`log(default, ?STD_IMPORTANCE, Format, [], [])`](`log/5`).".
 -spec log(Format) -> ok
       when Format :: string().
 log(Format) ->
@@ -750,7 +748,7 @@ printed with this function, unless the `esc_chars` option is used.
 log(Category,Importance,Format,Args,Opts) ->
     ct_logs:tc_log(Category,Importance,Format,Args,Opts).
 
--doc(#{equiv => print(default, ?STD_IMPORTANCE, Format, [], [])}).
+-doc "Equivalent to [`print(default, ?STD_IMPORTANCE, Format, [], [])`](`print/5`).".
 -spec print(Format) -> ok
       when Format :: string().
 print(Format) ->
@@ -835,7 +833,7 @@ the User's Guide.
 print(Category,Importance,Format,Args,Opts) ->
     ct_logs:tc_print(Category,Importance,Format,Args,Opts).
 
--doc(#{equiv => pal(default, ?STD_IMPORTANCE, Format, [], [])}).
+-doc "Equivalent to [`pal(default, ?STD_IMPORTANCE, Format, [])`](`pal/4`).".
 -spec pal(Format) -> ok
       when Format :: string().
 pal(Format) ->
diff --git a/lib/common_test/src/ct_cover.erl b/lib/common_test/src/ct_cover.erl
index 738a86a7a5d6..d64e4c291b83 100644
--- a/lib/common_test/src/ct_cover.erl
+++ b/lib/common_test/src/ct_cover.erl
@@ -20,8 +20,6 @@
 
 -module(ct_cover).
 -moduledoc """
-Common Test framework code coverage support module.
-
 `Common Test` framework code coverage support module.
 
 This module exports help functions for performing code coverage analysis.
diff --git a/lib/common_test/src/ct_ftp.erl b/lib/common_test/src/ct_ftp.erl
index 36e05390a276..ec1fcc35333f 100644
--- a/lib/common_test/src/ct_ftp.erl
+++ b/lib/common_test/src/ct_ftp.erl
@@ -20,8 +20,6 @@
 
 -module(ct_ftp).
 -moduledoc """
-FTP client module (based on the FTP application).
-
 FTP client module (based on the `ftp` application).
 """.
 
@@ -38,7 +36,7 @@ FTP client module (based on the `ftp` application).
 
 -define(DEFAULT_PORT,21).
 
--doc "For `target_name`, see module `m:ct`.".
+-doc "Reference to opened FTP connection associated to either a `handle` or `target_name`.".
 -type connection() :: handle() | ct:target_name().
 -doc "Handle for a specific FTP connection, see module `m:ct`.".
 -type handle() :: ct:handle().
@@ -52,8 +50,6 @@ Opens an FTP connection and sends a file to the remote host.
 
 `LocalFile` and `RemoteFile` must be absolute paths.
 
-For `target_name`, see module `m:ct`.
-
 If the target host is a "special" node, the FTP address must be specified in the
 configuration file as follows:
 
@@ -73,7 +69,7 @@ configuration file must also include the username and password (both strings):
 See also `ct:require/2`.
 """.
 -spec put(KeyOrName, LocalFile, RemoteFile) -> 'ok' | {'error', Reason}
-              when KeyOrName :: atom(),
+              when KeyOrName :: ct:key_or_name(),
                    LocalFile :: file:filename(),
                    RemoteFile :: file:filename(),
                    Reason :: term().
@@ -88,12 +84,10 @@ Opens an FTP connection and fetches a file from the remote host.
 
 The configuration file must be as for [`ct_ftp:put/3`](`put/3`).
 
-For `target_name`, see module `m:ct`.
-
 See also `ct:require/2`.
 """.
 -spec get(KeyOrName, RemoteFile, LocalFile) -> 'ok' | {'error', Reason}
-              when KeyOrName :: atom(),
+              when KeyOrName :: ct:key_or_name(),
                    RemoteFile :: file:filename(),
                    LocalFile :: file:filename(),
                    Reason :: term().
@@ -112,11 +106,9 @@ the target. A connection without an associated target name can only be closed
 with the handle value.
 
 For information on how to create a new `Name`, see `ct:require/2`.
-
-For `target_name`, see module `m:ct`.
 """.
 -spec open(KeyOrName) -> {'ok', Handle} | {'error', Reason}
-              when KeyOrName :: atom(),
+              when KeyOrName :: ct:key_or_name(),
                    Handle :: handle(),
                    Reason :: term().
 open(KeyOrName) ->
diff --git a/lib/common_test/src/ct_hooks.erl b/lib/common_test/src/ct_hooks.erl
index a665d9f5538d..638f6d818bbd 100644
--- a/lib/common_test/src/ct_hooks.erl
+++ b/lib/common_test/src/ct_hooks.erl
@@ -126,7 +126,7 @@ That is:
 - If a test case is skipped, this function is called after
   [`post_end_per_testcase`](`c:post_end_per_testcase/5`).
 
-If the skipped test case belongs to a test case group, the first argument is a
+If the skipped test case belongs to a test case group, the second argument is a
 tuple `{FuncName,GroupName}`, otherwise only the function name.
 
 The data that comes with `Reason` follows the same format as events
@@ -163,7 +163,7 @@ That is:
 - If a test case fails, this function is called after
   [`post_end_per_testcase`](`c:post_end_per_testcase/5`).
 
-If the failed test case belongs to a test case group, the first argument is a
+If the failed test case belongs to a test case group, the second argument is a
 tuple `{FuncName,GroupName}`, otherwise only the function name.
 
 The data that comes with `Reason` follows the same format as
diff --git a/lib/common_test/src/ct_master.erl b/lib/common_test/src/ct_master.erl
index 36d9924fdb30..271b834fc33e 100644
--- a/lib/common_test/src/ct_master.erl
+++ b/lib/common_test/src/ct_master.erl
@@ -20,8 +20,6 @@
 
 -module(ct_master).
 -moduledoc """
-Distributed test execution control for Common Test.
-
 Distributed test execution control for `Common Test`.
 
 This module exports functions for running `Common Test` nodes on multiple hosts
@@ -43,6 +41,7 @@ in parallel.
 -include("ct_event.hrl").
 -include("ct_util.hrl").
 
+-doc "Filename of test spec to be executed.".
 -type test_spec() :: file:name_all().
 
 -record(state, {node_ctrl_pids=[],
diff --git a/lib/common_test/src/ct_property_test.erl b/lib/common_test/src/ct_property_test.erl
index 053fb5b7061d..e2c82c354cae 100644
--- a/lib/common_test/src/ct_property_test.erl
+++ b/lib/common_test/src/ct_property_test.erl
@@ -93,9 +93,17 @@ prop_ftp() ->
         ]).
 
 %% Type declarations
+-type arguments() :: [term()].
+-type function_name() :: atom().
+-type symbolic_var() :: {'var', pos_integer()}.
+-type symbolic_call() :: {'call', module(), function_name(), arguments()}.
+-type symbolic_state() :: term().
 -type dynamic_state()     :: term().
--type command()           :: term().
+-type set_command() :: {'set', symbolic_var(), symbolic_call()}.
+-type init_command() :: {'init', symbolic_state()}.
+-type command()           :: set_command() | init_command().
 -type command_list()      :: [command()].
+-type parallel_testcase() :: {command_list(), [command_list()]}.
 -type history()           :: [term()].
 -type statem_result()     :: 'ok' | term().
 
@@ -233,7 +241,7 @@ quickcheck(Property, Config) ->
 -doc(#{equiv => present_result(Module, Cmds, Triple, Config, []), since => <<"OTP 22.3">>}).
 -spec present_result(Module, Cmds, Triple, Config) -> boolean()
               when Module :: module(),
-                   Cmds :: command() | command_list(),
+                   Cmds :: command_list() | parallel_testcase(),
                    Triple :: {H, Sf, Result},
                    H :: history(),
                    Sf :: dynamic_state(),
@@ -315,7 +323,7 @@ The default `StatisticsSpec` is:
 -doc(#{since => <<"OTP 22.3">>}).
 -spec present_result(Module, Cmds, Triple, Config, Options0) -> boolean()
               when Module :: module(),
-                   Cmds :: command() | command_list(),
+                   Cmds :: command_list() | parallel_testcase(),
                    Triple :: {H, Sf, Result},
                    H :: history(),
                    Sf :: dynamic_state(),
@@ -361,6 +369,7 @@ print_frequency() ->
 print_frequency_ranges() ->
     print_frequency_ranges([{ngroups,10}]).
 
+-doc false.
 print_frequency_ranges(Options0) ->
     fun([]) ->
             io_lib:format('Empty list!~n',[]);
@@ -374,6 +383,45 @@ print_frequency_ranges(Options0) ->
             end
     end.
 
+-doc """
+Returns a list of commands (function calls) generated in the `Cmnd` sequence,
+without Module, Arguments and other details.
+
+For more information see: `present_result/5`.
+""".
+-doc #{since => "OTP @OTP-19148@"}.
+-spec cmnd_names(Cs) -> Result when
+    Cs :: command_list() | parallel_testcase(),
+    Result :: [function_name()].
+cmnd_names(Cs) -> traverse_commands(fun cmnd_name/1, Cs).
+cmnd_name(L) ->  [F || {set,_Var,{call,_Mod,F,_As}} <- L].
+    
+-doc """
+Returns number of command calls in a test case.
+
+For more information see: `present_result/5`.
+""".
+-doc #{since => "OTP @OTP-19148@"}.
+-spec num_calls(Cs) -> Result when
+    Cs :: command_list() | parallel_testcase(),
+    Result :: [non_neg_integer()].
+num_calls(Cs) -> traverse_commands(fun num_call/1, Cs).
+num_call(L) -> [length(L)].
+    
+-doc """
+Returns a list with information about sequential and parallel parts.
+
+For more information see: `present_result/5`.
+""".
+-doc #{since => "OTP @OTP-19148@"}.
+-spec sequential_parallel(Cs) -> Result when
+    Cs :: command_list() | parallel_testcase(),
+    Result :: [atom()].
+sequential_parallel(Cs) ->
+    traverse_commands(fun(L) -> dup_module(L, sequential) end,
+		      fun(L) -> [dup_module(L1, mkmod("parallel",num(L1,L))) || L1<-L] end,
+		      Cs).
+
 %%%================================================================
 %%%
 %%% Local functions
@@ -483,19 +531,6 @@ do_present_result(Module, Cmds, H, Sf, Result, _Config, Options) ->
     Result == ok. % Proper dislikes non-boolean results while eqc treats non-true as false.
 
 %%%================================================================
--doc false.
-cmnd_names(Cs) -> traverse_commands(fun cmnd_name/1, Cs).
-cmnd_name(L) ->  [F || {set,_Var,{call,_Mod,F,_As}} <- L].
-    
--doc false.
-num_calls(Cs) -> traverse_commands(fun num_call/1, Cs).
-num_call(L) -> [length(L)].
-    
--doc false.
-sequential_parallel(Cs) ->
-    traverse_commands(fun(L) -> dup_module(L, sequential) end,
-		      fun(L) -> [dup_module(L1, mkmod("parallel",num(L1,L))) || L1<-L] end,
-		      Cs).
 dup_module(L, ModName) -> lists:duplicate(length(L), ModName).
 mkmod(PfxStr,N) -> list_to_atom(PfxStr++"_"++integer_to_list(N)).
     
diff --git a/lib/common_test/src/ct_rpc.erl b/lib/common_test/src/ct_rpc.erl
index 7ca5d9080c10..e381ecefb3ed 100644
--- a/lib/common_test/src/ct_rpc.erl
+++ b/lib/common_test/src/ct_rpc.erl
@@ -20,8 +20,6 @@
 
 -module(ct_rpc).
 -moduledoc """
-Common Test specific layer on Erlang/OTP rpc.
-
 `Common Test` specific layer on Erlang/OTP `rpc`.
 """.
 
diff --git a/lib/common_test/src/ct_slave.erl b/lib/common_test/src/ct_slave.erl
index 2235432d155a..c361bb90a233 100644
--- a/lib/common_test/src/ct_slave.erl
+++ b/lib/common_test/src/ct_slave.erl
@@ -25,9 +25,6 @@
 %%----------------------------------------------------------------------
 -module(ct_slave).
 -moduledoc """
-Common Test framework functions for starting and stopping nodes for Large-Scale
-Testing.
-
 `Common Test` framework functions for starting and stopping nodes for
 Large-Scale Testing.
 
@@ -48,6 +45,7 @@ term in the Test Specification.
 		  kill_if_fail, erl_flags, env, ssh_port, ssh_opts,
 		  stop_timeout}).
 
+-doc "Options used for starting `ct_slave` node.".
 -type start_options() :: [{'username', string()}
                          | {'password', string()}
                          | {'boot_timeout', non_neg_integer()}
@@ -61,6 +59,7 @@ term in the Test Specification.
                          | {'ssh_port', inet:port_number()}
                          | {'ssh_opts', ssh:client_options()}].
 
+-doc "Options used for stopping `ct_slave` node.".
 -type stop_options() :: [{'stop_timeout', non_neg_integer()}].
 
 -export_type([start_options/0, stop_options/0]).
diff --git a/lib/common_test/src/ct_snmp.erl b/lib/common_test/src/ct_snmp.erl
index 439c7aa6d0c9..a94f724439c1 100644
--- a/lib/common_test/src/ct_snmp.erl
+++ b/lib/common_test/src/ct_snmp.erl
@@ -20,8 +20,6 @@
 
 -module(ct_snmp).
 -moduledoc """
-Common Test user interface module for the SNMP application.
-
 `Common Test` user interface module for the `SNMP` application.
 
 The purpose of this module is to simplify SNMP configuration for the test case
diff --git a/lib/common_test/src/ct_ssh.erl b/lib/common_test/src/ct_ssh.erl
index fa031b943f8b..4ab1a08175c1 100644
--- a/lib/common_test/src/ct_ssh.erl
+++ b/lib/common_test/src/ct_ssh.erl
@@ -90,16 +90,20 @@ All time-out parameters in `ct_ssh` functions are values in milliseconds.
 
 -doc "Handle for a specific SSH/SFTP connection, see module `m:ct`.".
 -type handle() :: pid().
--doc "For `target_name`, see module `m:ct`.".
+-doc "Reference to opened SSH/SFTP connection associated to either a `handle` or `target_name`.".
 -type connection() :: handle() | ct:target_name().
--doc "Connection type used for connect".
+-doc "Connection type used for connect.".
 -type connection_type() :: 'host' | 'ssh' | 'sftp'.
 -doc """
 The valid values are `0` ("normal") and `1` ("stderr"), see
-[RFC 4254, Section 5.2](https://tools.ietf.org/html/rfc4254#page/8).
+[RFC 4254, Section 5.2](https://tools.ietf.org/html/rfc4254#page-8).
 """.
 -type ssh_data_type_code() :: non_neg_integer().
--doc "For `ssh_channel_id`, see module `m:ssh`.".
+-doc """
+Data type representing a channel inside a connection.
+
+"For `ssh_channel_id`, see module `m:ssh`.".
+""".
 -type ssh_channel_id() :: non_neg_integer().
 
 %%%-----------------------------------------------------------------
@@ -107,7 +111,7 @@ The valid values are `0` ("normal") and `1` ("stderr"), see
 
 -doc(#{equiv => connect(KeyOrName, host, [])}).
 -spec connect(KeyOrName) -> {'ok', Handle} | {'error', Reason}
-              when KeyOrName :: atom(),
+              when KeyOrName :: ct:key_or_name(),
                    Handle :: handle(),
                    Reason :: term().
 connect(KeyOrName) ->
@@ -124,12 +128,12 @@ Equivalent to [`connect(KeyOrName, host, ExtraOpts)`](`connect/3`) if
 called with ExtraOpts being list.
 """.
 -spec connect(KeyOrName, ConnType) -> {'ok', Handle} | {'error', Reason}
-              when KeyOrName :: atom(),
+              when KeyOrName :: ct:key_or_name(),
                    ConnType :: connection_type(),
                    Handle :: handle(),
                    Reason :: term();
              (KeyOrName, ExtraOpts) -> {'ok', Handle} | {'error', Reason}
-              when KeyOrName :: atom(),
+              when KeyOrName :: ct:key_or_name(),
                    ExtraOpts :: [ExtraOption],
                    ExtraOption :: {'ssh', Address} | {'sftp', Address} | ssh:client_option()
                                 | ssh_sftp:sftp_option(),
@@ -154,8 +158,6 @@ opened using the configuration data specified by `Key`).
 
 For information on how to create a new `Name`, see `ct:require/2`.
 
-For `target_name`, see module `m:ct`.
-
 `ConnType` always overrides the type specified in the address tuple in the
 configuration data (and in `ExtraOpts`). So it is possible to, for example, open
 an SFTP connection directly using data originally specifying an SSH connection.
@@ -168,7 +170,7 @@ same key in the configuration data. For details on valid SSH options, see
 application [`SSH`](`e:ssh:index.html`).
 """.
 -spec connect(KeyOrName, ConnType, ExtraOpts) -> {'ok', Handle} | {'error', Reason}
-              when KeyOrName :: atom(),
+              when KeyOrName :: ct:key_or_name(),
                    ConnType :: connection_type(),
                    ExtraOpts :: [ExtraOption],
                    ExtraOption :: {'ssh', Address} | {'sftp', Address} | ssh:client_option()
@@ -629,7 +631,7 @@ shell(SSH, ChannelId) ->
     shell(SSH, ChannelId, ?DEFAULT_TIMEOUT).
 
 -doc """
-Requests that the user default shell (typically defined in `/etc/passwd` in Unix
+Requests that the user's default shell (typically defined in `/etc/passwd` in Unix
 systems) is executed at the server end.
 """.
 -doc(#{since => <<"OTP 20.0">>}).
diff --git a/lib/common_test/src/ct_suite.erl b/lib/common_test/src/ct_suite.erl
index 28d4aa1a6f9a..1921a2d15765 100644
--- a/lib/common_test/src/ct_suite.erl
+++ b/lib/common_test/src/ct_suite.erl
@@ -1,7 +1,5 @@
 -module(ct_suite).
 -moduledoc """
-\-behaviour(ct_suite).
-
 The following section describes the mandatory and optional test suite functions
 that `Common Test` calls during test execution. For more details, see section
 [Writing Test Suites](write_test_chapter.md) in the User's Guide.
@@ -96,7 +94,9 @@ The test suite information, as returned by [`Module:suite/0`](`c:suite/0`),
 
 -doc """
 Returns the list of all test cases and test case groups in the test suite module
-to be executed. This list also specifies the order the cases and groups are
+to be executed.
+
+This list also specifies the order the cases and groups are
 executed by `Common Test`. A test case is represented by an atom, the name of
 the test case function, or a `testcase` tuple indicating that the test case
 shall be repeated. A test case group is represented by a `group` tuple, where
@@ -163,12 +163,11 @@ Guide.
     [Info :: ct_info()].
 
 -doc """
-OPTIONAL; if this function is defined, then
-[`Module:end_per_suite/1`](`c:end_per_suite/1`) must also be defined.
-
 This configuration function is called as the first function in the suite. It
 typically contains initializations that are common for all test cases in the
-suite, and that must only be done once. Parameter `Config` is the configuration
+suite, and that must only be done once.
+
+Parameter `Config` is the configuration
 data that can be modified. Whatever is returned from this function is specified
 as `Config` to all configuration functions and test cases in the suite.
 
@@ -178,6 +177,9 @@ If `{skip, Reason}` is returned, all test cases in the suite are skipped and
 For information on `save_config` and `skip_and_save`, see section
 [Saving Configuration Data](dependencies_chapter.md#save_config) in the User's
 Guide.
+
+If this function is defined, then
+[`Module:end_per_suite/1`](`c:end_per_suite/1`) must also be defined.
 """.
 -doc(#{title => <<"Callback Functions">>}).
 -callback init_per_suite(Config :: ct_config()) ->
@@ -186,15 +188,15 @@ Guide.
     {skip_and_save, Reason :: term(), SaveConfig :: ct_config()}.
 
 -doc """
-OPTIONAL; if this function is defined, then
-[`Module:init_per_suite/1`](`c:init_per_suite/1`) must also be defined.
-
 This function is called as the last test case in the suite. It is meant to be
 used for cleaning up after [`Module:init_per_suite/1`](`c:init_per_suite/1`).
 
 For information on `save_config`, see section
 [Saving Configuration Data](dependencies_chapter.md#save_config) in the User's
 Guide.
+
+If this function is defined, then
+[`Module:init_per_suite/1`](`c:init_per_suite/1`) must also be defined.
 """.
 -doc(#{title => <<"Callback Functions">>}).
 -callback end_per_suite(Config :: ct_config()) ->
@@ -240,13 +242,11 @@ Guide.
     [Info :: ct_info()].
 
 -doc """
-OPTIONAL; if this function is defined, then
-[`Module:end_per_group/2`](`c:end_per_group/2`) must also be defined.
-
 This configuration function is called before execution of a test case group. It
 typically contains initializations that are common for all test cases and
-subgroups in the group, and that must only be performed once. `GroupName` is the
-name of the group, as specified in the group definition (see
+subgroups in the group, and that must only be performed once.
+
+`GroupName` is the name of the group, as specified in the group definition (see
 [`Module:groups/0`](`c:groups/0`)). Parameter `Config` is the configuration data
 that can be modified. The return value of this function is given as `Config` to
 all test cases and subgroups in the group.
@@ -256,6 +256,9 @@ If `{skip, Reason}` is returned, all test cases in the group are skipped and
 
 For information about test case groups, see section
 [Test Case Groups](write_test_chapter.md#test_case_groups) in the User's Guide.
+
+If this function is defined, then
+[`Module:end_per_group/2`](`c:end_per_group/2`) must also be defined.
 """.
 -doc(#{title => <<"Callback Functions">>}).
 -callback init_per_group(GroupName :: ct_groupname(), Config :: ct_config()) ->
@@ -263,20 +266,20 @@ For information about test case groups, see section
     {skip, Reason :: term()}.
 
 -doc """
-OPTIONAL; if this function is defined, then
-[`Module:init_per_group/2`](`c:init_per_group/2`) must also be defined.
-
 This function is called after the execution of a test case group is finished. It
-is meant to be used for cleaning up after
-[`Module:init_per_group/2`](`c:init_per_group/2`). A status value for a nested
-subgroup can be returned with `{return_group_result, Status}`. The status can be
-retrieved in [`Module:end_per_group/2`](`c:end_per_group/2`) for the group on
+is meant to be used for cleaning up after [`Module:init_per_group/2`](`c:init_per_group/2`).
+
+A status value for a nested subgroup can be returned with `{return_group_result, Status}`.
+The status can be retrieved in [`Module:end_per_group/2`](`c:end_per_group/2`) for the group on
 the level above. The status is also used by `Common Test` for deciding if
 execution of a group is to proceed if property `sequence` or `repeat_until_*` is
 set.
 
 For details about test case groups, see section
 [Test Case Groups](write_test_chapter.md#test_case_groups) in the User's Guide.
+
+If this function is defined, then
+[`Module:init_per_group/2`](`c:init_per_group/2`) must also be defined.
 """.
 -doc(#{title => <<"Callback Functions">>}).
 -callback end_per_group(GroupName :: ct_groupname(), Config :: ct_config()) ->
@@ -284,17 +287,19 @@ For details about test case groups, see section
     {return_group_result, Status :: ct_status()}.
 
 -doc """
-OPTIONAL; if this function is defined, then
-[`Module:end_per_testcase/2`](`c:end_per_testcase/2`) must also be defined.
+This function is called before each test case.
+
+Argument `TestCase` is the test case name, and `Config` (list of key-value tuples)
+is the configuration data that can be modified. The `NewConfig` list returned from this
+function is given as `Config` to the test case.
 
-This function is called before each test case. Argument `TestCase` is the test
-case name, and `Config` (list of key-value tuples) is the configuration data
-that can be modified. The `NewConfig` list returned from this function is given
-as `Config` to the test case. If `{fail, Reason}` is returned, the test case is
-marked as failed without being executed.
+If `{fail, Reason}` is returned, the test case is marked as failed without being executed.
 
 If `{skip, Reason}` is returned, the test case is skipped and `Reason` is
 printed in the overview log for the suite.
+
+If this function is defined, then
+[`Module:end_per_testcase/2`](`c:end_per_testcase/2`) must also be defined.
 """.
 -doc(#{title => <<"Callback Functions">>}).
 -callback init_per_testcase(TestCase :: ct_testname(), Config :: ct_config()) ->
@@ -303,12 +308,10 @@ printed in the overview log for the suite.
     {skip, Reason :: term()}.
 
 -doc """
-OPTIONAL; if this function is defined, then
-[`Module:init_per_testcase/2`](`c:init_per_testcase/2`) must also be defined.
-
 This function is called after each test case, and can be used to clean up after
-[`Module:init_per_testcase/2`](`c:init_per_testcase/2`) and the test case. Any
-return value (besides `{fail, Reason}` and `{save_config, SaveConfig}`) is
+[`Module:init_per_testcase/2`](`c:init_per_testcase/2`) and the test case.
+
+Any return value (besides `{fail, Reason}` and `{save_config, SaveConfig}`) is
 ignored. By returning `{fail, Reason}`, `TestCase` is marked as faulty (even
 though it was successful in the sense that it returned a value instead of
 terminating).
@@ -316,6 +319,9 @@ terminating).
 For information on `save_config`, see section
 [Saving Configuration Data](dependencies_chapter.md#save_config) in the User's
 Guide.
+
+If this function is defined, then
+[`Module:init_per_testcase/2`](`c:init_per_testcase/2`) must also be defined.
 """.
 -doc(#{title => <<"Callback Functions">>}).
 -callback end_per_testcase(TestCase :: ct_testname(), Config :: ct_config()) ->
diff --git a/lib/common_test/src/ct_telnet.erl b/lib/common_test/src/ct_telnet.erl
index b0e000f92be2..6523e1d4b9dc 100644
--- a/lib/common_test/src/ct_telnet.erl
+++ b/lib/common_test/src/ct_telnet.erl
@@ -20,8 +20,6 @@
 
 -module(ct_telnet).
 -moduledoc """
-Common Test specific layer on top of Telnet client ct_telnet_client.erl
-
 `Common Test` specific layer on top of Telnet client `ct_telnet_client.erl`.
 
 Use this module to set up Telnet connections, send commands, and perform string
@@ -176,8 +174,9 @@ suite() ->
 
 -include("ct_util.hrl").
 
--doc "For `target_name()`, see module `m:ct`.".
+-doc "Reference to opened Telnet connection associated to either a `handle` or `target_name`.".
 -type connection() :: handle() | {ct:target_name(), connection_type()} | ct:target_name().
+-doc "Telnet connection_type, valid values: 'telnet' | 'ts1' | 'ts2'.".
 -type connection_type() :: telnet | ts1 | ts2.
 -doc "Handle for a specific Telnet connection, see module `m:ct`.".
 -type handle() :: ct:handle().
@@ -187,7 +186,8 @@ Regular expression matching all possible prompts for a specific target type.
 STDLIB) must return a list with one single element.
 """.
 -type prompt_regexp() :: string().
--type send_option() :: {'newline', boolean() | string()}.
+-doc "See `cmd/3` for explanation.".
+-type newline_option() :: {'newline', boolean() | string()}.
 -export_type([connection/0, connection_type/0, handle/0, prompt_regexp/0]).
 
 -record(state,{host,
@@ -237,7 +237,7 @@ open(Name,ConnType) ->
 
 -doc(#{equiv => open(KeyOrName, ConnType, TargetMod, KeyOrName)}).
 -spec open(KeyOrName, ConnType, TargetMod) -> {'ok', Handle} | {'error', Reason}
-              when KeyOrName :: atom(),
+              when KeyOrName :: ct:key_or_name(),
                    ConnType :: connection_type(),
                    TargetMod :: module(),
                    Handle :: handle(),
@@ -265,12 +265,10 @@ without an associated target name can only be closed with the `Handle` value.
 `connect(Ip, Port, KeepAlive, Extra)` and `get_prompt_regexp()` for the
 specified `TargetType` (for example, `unix_telnet`).
 
-For `target_name()`, see module `m:ct`.
-
 See also `ct:require/2`.
 """.
 -spec open(KeyOrName, ConnType, TargetMod, Extra) -> {'ok', Handle} | {'error', Reason}
-              when KeyOrName :: atom(),
+              when KeyOrName :: ct:key_or_name(),
                    ConnType :: connection_type(),
                    TargetMod :: module(),
                    Extra :: term(),
@@ -371,7 +369,7 @@ module.
 -spec cmd(Connection, Cmd, Opts) -> {'ok', Data} | {'error', Reason}
               when Connection :: connection(),
                    Cmd :: iodata(),
-                   Opts :: [{'timeout', Timeout} | send_option()] | Timeout,
+                   Opts :: [{'timeout', Timeout} | newline_option()] | Timeout,
                    Timeout :: integer(),
                    Data :: string(),
                    Reason :: term().
@@ -419,7 +417,7 @@ For details, see [`ct_telnet:cmd/3`](`cmd/3`).
               when Connection :: connection(),
                    CmdFormat :: io:format(),
                    Args :: [term()],
-                   Opts :: [{'timeout', Timeout} | send_option()] | Timeout,
+                   Opts :: [{'timeout', Timeout} | newline_option()] | Timeout,
                    Timeout :: integer(),
                    Data :: string(),
                    Reason :: term().
@@ -475,7 +473,7 @@ The resulting output from the command can be read with
 -spec send(Connection, Cmd, Opts) -> 'ok' | {'error', Reason}
               when Connection :: connection(),
                    Cmd :: iodata(),
-                   Opts :: [send_option()],
+                   Opts :: [newline_option()],
                    Reason :: term().
 send(Connection,Cmd,Opts) ->
     case check_send_opts(Opts) of
@@ -526,7 +524,7 @@ For details, see [`ct_telnet:send/3`](`send/3`).
               when Connection :: connection(),
                    CmdFormat :: io:format(),
                    Args :: [term()],
-                   Opts :: [send_option()],
+                   Opts :: [newline_option()],
                    Reason :: term().
 sendf(Connection,CmdFormat,Args,Opts) when is_list(Args) ->
     Cmd = lists:flatten(io_lib:format(CmdFormat,Args)),
diff --git a/lib/common_test/src/ct_testspec.erl b/lib/common_test/src/ct_testspec.erl
index 6679036ef8c7..0af4fc844813 100644
--- a/lib/common_test/src/ct_testspec.erl
+++ b/lib/common_test/src/ct_testspec.erl
@@ -20,8 +20,6 @@
 
 -module(ct_testspec).
 -moduledoc """
-Parsing of test specifications for Common Test.
-
 Parsing of test specifications for `Common Test`.
 
 This module exports help functions for parsing of test specifications.
diff --git a/lib/common_test/src/unix_telnet.erl b/lib/common_test/src/unix_telnet.erl
index d5bcec211085..862f4e0505b2 100644
--- a/lib/common_test/src/unix_telnet.erl
+++ b/lib/common_test/src/unix_telnet.erl
@@ -20,8 +20,6 @@
 
 -module(unix_telnet).
 -moduledoc """
-Callback module for ct_telnet, for connecting to a Telnet server on a UNIX host.
-
 Callback module for `m:ct_telnet`, for connecting to a Telnet server on a UNIX
 host.
 
@@ -79,11 +77,9 @@ Callback for `ct_telnet.erl`.
 
 Returns a suitable `regexp` string matching common prompts for users on Unix
 hosts.
-
-For `prompt_regexp()`, see `m:ct_telnet`.
 """.
 -spec get_prompt_regexp() -> Pattern
-              when Pattern :: string().
+              when Pattern :: ct_telnet:prompt_regexp().
 get_prompt_regexp() ->
     ?prx.
 
@@ -93,8 +89,6 @@ Callback for `ct_telnet.erl`.
 [](){: #connect-6 }
 
 Setup Telnet connection to a Unix host.
-
-For `target_name()`, see `m:ct`. For `handle()`, see `m:ct_telnet`.
 """.
 -doc(#{since => <<"OTP 18.3.3">>}).
 -spec connect(ConnName, Ip, Port, Timeout, KeepAlive, TCPNoDelay, Extra) ->
@@ -108,7 +102,7 @@ For `target_name()`, see `m:ct`. For `handle()`, see `m:ct_telnet`.
                    Extra :: {Username, Password} | KeyOrName,
                    Username :: iodata(),
                    Password :: iodata(),
-                   KeyOrName :: atom(),
+                   KeyOrName :: ct:key_or_name(),
                    Handle :: ct_telnet:handle(),
                    Reason :: term().
 connect(ConnName,Ip,Port,Timeout,KeepAlive,TCPNoDelay,Extra) ->
diff --git a/lib/ssh/src/ssh_connection.erl b/lib/ssh/src/ssh_connection.erl
index d96cc06639bc..8849f29575cc 100644
--- a/lib/ssh/src/ssh_connection.erl
+++ b/lib/ssh/src/ssh_connection.erl
@@ -127,7 +127,7 @@ If not, the `t:reason/0` indicates what went wrong:
 
 -doc """
 The valid values are `0` ("normal") and `1` ("stderr"), see
-[RFC 4254, Section 5.2](https://tools.ietf.org/html/rfc4254#page/8).
+[RFC 4254, Section 5.2](https://tools.ietf.org/html/rfc4254#page-8).
 """.
 -type ssh_data_type_code() :: non_neg_integer(). % Only 0 and 1 are used